Assessing the Suitability of Context
Information for Ambient Display
Steve Neely, Graeme Stevenson, and Paddy Nixon
Systems Research Group
University College Dublin
Belfield, Dublin, Ireland
+353 1 716 5348
{firstname.lastname}@ucd.ie

ABSTRACT
With the advance of pervasive technology, information
from both the physical and virtual world is increasingly
accessible to developers. Context -aware applications may
consume relevant aspects of this information as they
support user tasks. When conveying information to people,
the mechanism for presentation must be carefully
considered. As ambient devices are centred on the notion
of calm-technology, it is logical that certain types of data
lend themselves to ambient display more easily than others.
In this paper we present our initial investigations into the
properties of contextual information best suited for display
using ambient technologies. We present the feature set
extracted from our investigation, and apply examples that
satisfy these criteria to our prototype ambient device, the
visual calendar.
Keywords
Context, ambient devices, pervasive computing
INTRODUCTION
The boundary between personal computing and consumer
electronic devices is becoming increasingly blurred,
resulting in an environment in which technology is blended
with everyday objects [1]. In addition to easing the path
through which data from the physical world may be
combined with data from the virtual world, application
developers are afforded new opportunities for interacting
with users outwith the bounds of the traditional personal
computer.
Our recent work has focused on the development of
frameworks that support the collection and distribution of
context information , and on raising the level of abstraction
over data that is available to applications [2]. Early
applications that we developed made use of web pages,
mobile devices, and wall-mounted displays to present
information to and interact with users. We are presently
investigating the use of ambient displays, and examining
how they afford different opportunities for presenting
context information to users in comparison with existing
approaches.
Our notion of an ambient display is based around Weiser’s
idea of calm-technology [3]. With respect to this tenet, we
take the view that ambient displays should be designed to
be unobtrusive, with interaction completely driven by the
user. They should be experienced as a tool that the user
may refer to in the process of completing a task if he or she
wishes.
Information manifests itself in many forms. It may appear in
a single or number of discrete events, or flow as a
continuous stream. Values may be relatively static or highly
dynamic over time. The range covered by data may take the
form of a finite set of values or have unbounded scale.
Information must be appropriately represented for it to be
understood by the user. This implies the need for a strong
correlation between the nature of information and its
presentation medium. As ambient devices adhere to the
concept of calm-technology, it follows that certain types of
data are more appropriate for ambient display than others.
In this paper we present our initial research towards
identifying properties of context information that are well-
suited for presentation via ambient technology. We
consider the mapping between information and realisation
by existing devices, and the need to “ask the right
question” of the information. Throughout this paper we use
examples of readily available sources of information to
motivate discussion, and apply examples of information that
match these properties to a prototype ambient device, the
visual calendar.
This paper is structured as follows: In section 2 we discuss
the mapping between information and display in existing
ambient devices. Section 3 presents our initial investigation
into the properties of context information best suited for
ambient display. Section 4 describes the application of
different types of information to a prototype ambient
display. Finally, in section 5 we summarise our work and
present a question designed to motivate discussion at the
workshop.



Copyright is held by the authors.
Pervasive '07 Workshop: W9 - Ambient Information Systems
May 13, 2007; Toronto, Ontario, Canada
This position paper is not an official publication of

RELATED WORK
There are many examples of ambient devices that aim to
communicate a wide rage of information to users without
placing significant demands on their attention. This section
examines some well-known examples, and discusses the
relationship between information source and display
technology.
Ambient Devices’ Ambient Orb [4] is a glass ball that
changes colour to display variance in data obtained from
internet sources. The Orb has many modes, which makes it
an interesting case study. As an example of an intuitive and
useful mapping, the Orb will change colour from green,
through yellow, to red to indicate current traffic congestion
levels. A less complete visualisation is the mode that
displays changes to a stock portfolio, which is restricted to
indicating performance swings of up to 2.5%. External
information, namely the starting value of the stocks, is
required for the interpretation to be fully meaningful.
Finally, the Orb’s weather forecast mode uses 11 different
colours to indicate temperature intervals between -10 and
100 degrees Fahrenheit. When there is a chance of
precipitation the Orb pulses. This more complex
visualisation demonstrates that the Orb is not well matched
to the problem of conveying weather information.
van Mensvoort’s DataFountain [5] uses three water
fountains to provide a visual comparison of the Yen, Euro
and Dollar currency rates. Whilst it is an aesthetically
pleasing display, and is straightforward to deduce the
relative position of each currency, the scale on which the
fountains operate is not visualised. The nature of the
presentation medium greatly reduces the precision at which
the data can be interpreted.
Jafarinaimi et al.’s Breakaway project [6] uses a morphing
sculpture to encourage people with desk jobs to take breaks
throughout the day. Information gathered from sensors in
the user’s seat drives changes to the shape of the
sculpture. The sculpture is designed to mimic the human
body - when upright, it indicates that the body is refreshed;
when slouching, it represents that the user has been sitting
for an extended period of time. The sculpture reflects a good
mapping between information and its visualisation. The
intention of the sculpture is more easily interpreted than,
say, a numeric display of the time spent seated; providing a
visual clue that suggests the user takes a break.
Ardern’s Powerpoint [7] is a mains socket augmented with a
set of LEDs that indicate the amount of energy consumed
from the outlet. As the power consumption increases, the
number of lit LEDs increases, and their colour changes on a
spectrum between green and red. The intention is to
increase user awareness of power being drawn by various
appliances. Despite the fact that this mapping is intuitive,
the decision to place the display on the wall socket may be
questioned. There is an assumption that the socket is in full
view and not, for example, behind a sofa or a bookcase.
However, the idea of a central view for recording and
displaying information is touched upon.
Finally, Stasko et al’s InfoCanvas [8] allows people to
specify mappings between information of personal interest
and pictorial representations. These are realised in the form
of a digital painting. The artefacts in the painting move,
morph, or change colour to represent changes in state.
Some mappings are intuitive, such as changes in colours
representing traffic conditions. Others mappings, such as
those involving scalar data types, are difficult to interpret
visually without the presence of a scale. The InfoCanvas
example employs a kite at varying highs to represent rise
and fall of stock prices. Without a clear indicator as to the
exact values being represented, the stock price cannot be
read.
FEATURES OF CONTEXT DATA SUITABLE FOR AMBIENT
DISPLAY
Context information can be derived from any data that
describes the current state of a system, its users, and their
surrounding environment. Examples of such data are user
location, current task(s), goals, environmental conditions
(temperature, weather, light conditions), capabilities of the
system, and so on. When a user is the end point for
delivery of context information, the presentation mechanism
must be carefully considered. We hypothesise that ambient
technology is only suited to conveying certain types of
context information to the user. This section discusses five
properties of context information that should be considered
when selecting an appropriate presentation medium.
Precision is the first property that we consider. Ambient
displays do not lend themselves to accurately conveying
information with a fine granularity. A continuous range of
values needs a scale to be fully understood. Without a
scale, interpretation can only be approximate and precise
comparison between different states is difficult. Linear
scales may be represented where accuracy is not important,
but other scales, such as logarithmic, may be more difficult
to interpret. Where values are described from some offset,
such as stock price fluctuations, the user needs to have an
understanding of the base-level for that offset to make
sense. Ambient displays cannot clutter the visualisation
with scales for values or keys with labels, which increase
the cognitive load on the user. Information should be
instinctively interpretable without the requirement for extra
indicators to enable understanding. Context data needs to
be rounded or smoothed before displaying in a calm-
manner. A small, discrete set of values are far simpler to map
to a visualisation. Attempts to display a large number of
related values with fine resolution are inherently more open
to user reasoning error.

Criticality influences how aware the user must be with
respect to changes in the state of information. If the user
must pay significant attention to the information, the device
should not be regarded as ambient. Similarly, if a change in
information state requires immediate user attention, this too
should not be regarded as ambient. Presented information
must not be mission critical; it should be supportive of but
not integral to the tasks at hand. If ignorance of information
will cause the user’s task to fail, the information should be
presented in a more intrusive manner. The principle of calm-
technology behind ambient displays makes them a poor
mechanism for conveying data that must be acknowledged
or acted upon.
The periodicity of context information is another factor in
choosing appropriate presentation. Information that is
repeated often is suited to ambient display. In some sense,
repeated data is linked to the property of criticality. If the
user misses a particular assertion, a future event in the
sequence may be observed. Users should not be left
wondering if they have missed a rare event. For example,
train departure times between the user’s local station and
home may be a good example of repeated data.
The interpretability of context information is another factor.
Information usage should be considered a priori in order to
provide a representation that does not strain the user's
cognitive load. Information is only appropriate for ambient
display if it can be visualised in a way that lends itself to
easy interpretation. An example of this is a system designed
to show bus timetables. Displaying the raw data provides
too much information: the user needs to aggregate times of
buses with the current time and the time it will take to get to
the bus stop. It is more appropriate if the data is pre-
processed and conveyed in a personalised manner. Note
that we do not imply the display of bus timetables is not
useful, only that it is not ambient.
The final characteristic we consider is self-descriptiveness.
When displaying context information to the user it is
important to provide a stand-alone representation. The user
should not require information beyond what is displayed to
fully comprehend its meaning. We motivate this using two
of the AmbientOrb applications discussed in section 2. The
stock performance application provides an example of an
incomplete representation of context information, where the
user’s interpretation is restricted by the need to know the
starting price for the day. This can be contrasted with the
traffic congestion application, where the user requires no
external information to understand its meaning. The self-
descriptiveness and interpretability properties of context
information are closely related.
We observe that data-driven processes can be well-
supported through the use of ambient displays. This
encompasses situations where the aggregate of information
from multiple sources is considered useful to the user, and
the individual information not so. Aggregated data should
be displayed in the form that is most meaningful for the task
at hand. For example, a system that takes multiple inputs to
predict weather patterns may be of most use to the user by
answering the question: “should I carry an umbrella with me
today?” Boolean outputs such as these are examples of
context information well-suited for ambient display.
THE VISUAL CALENDAR EXAMPLE
We have designed a prototype ambient device called the
Visual Calendar, which provides users with a personalised
display of context information. The device is similar in
principal to the InfoCanvas [8], and takes the form of a
digital picture in which artefacts are placed that visualise
context information relevant to the user.
The visual calendar is realised using a widescreen display.
It provides a view of the state of the world relevant to the
user's current context through animated icons and symbols.
Context information is selected and processed to ensure
that it adheres to the feature set identified in the previous
section. This is illustrated in figure 1.
Artefacts in the foreground of the picture move from right
to left as time advances. They may take the form of either a
representation spanning the horizontal axis, or may appear
as a numb er of discrete values.

Figure 1: The timeline of the visual calendar.
The background of the picture is used to represent
contextual data viewed as a Boolean question. When
artefacts in the background are present, they indicate that a
condition is true; they disappear when the condition is
false. Reducing context information to a Boolean
representation satisfies the precision and interpretability
properties we outlined above. It is the responsibility of the
developer to ensure that the question being asked of the
context information is appropriate to satisfy the other
properties.
In our scenario, buses on the road represent the approach
of a bus on the user’s route home from work. The
visualisation takes into account the time required for the
user to walk to the bus stop, and the estimated time the bus
will reach the bus stop. Buses move along the road on the

display from right to left , each bus disappearing from view
once it is no longer possible for the user to catch it. Note
that this representation satisfies each of the criteria we set
out. The visualisation of the bus travelling along the road
provides adequate precision. No explicit scale is required,
as the user can interpret meaning from the position of the
bus on the road. Missing a bus is not important when
others will follow. This satisfies the criticality property of
the system. The timetable and user location data have been
pre-processed from their raw forms into a personalised
version. This yields a satisfactory degree of interpretability
as the system includes the time the user takes to get to a
bus stop. Simplicity of visualisation further meets this
requirement. The representation is also self-descriptive,
requiring no external information to be understood. It is
important to note that this representation may not be
suitable for all users at all times. For example, if the next bus
is the last (criticality), or there are only 2 buses a day
(periodicity).
Figure 1 also illustrates the use of the visual calendar to
display traffic congestion, and person location information.
The three buildings in the background represent home,
office, and school. When a family member is sensed in one
of these locations, their image appears in front of the
building. The cars travel along the road indicating current
and predicted traffic congestion on the route between the
user’s work and home. The number of cars on the road
indicates the current level of congestion, while cars stacked
closer together on the right edge of the road indicate that
congestion is expected within the next hour. Historical data
is used to predict congestion based on the day of the week
and the time of day. We believe that the number of cars on
the road clearly conveys whether there is congestion to the
user. There is no need to apply a fine-grained scale in order
to make the representation meaningful. As with the example
of the buses, if you miss a time period when the roads are
clear, another will follow. The nature of traffic flow follows
this repeated pattern, satisfying our criticality and
periodicity properties. Interpretability is eased by pre-
processing traffic reports for the user's route home from
work. The resultant visualisation, which uses cars, is simple
and self-descriptive - cars are a symptom of congestion and
therefore aid user understanding of the representation.
Finally, the three images in the upper-half of the display
represent weather forecasts for now, rest of today, and
tomorrow. These well-known representations satisfy all five
of the properties identified in this paper.
CONCLUSION
Increased availability of information from both the physical
and virtual world provides developers with new
opportunities for supporting user tasks. Ambient devices,
based around the notion of calm-technology, are one
approach to exposing such information to users. In this
paper we hypothesised that only certain types of context
information are suitable for display via ambient technology.
Our initial research into the properties of information that fit
this display modality has identified precision, criticality,
periodicity, interpretability and self-descriptiveness as key
factors. We illustrated our findings using a prototype
ambient device, the visual calendar.
We posit that it is important to consider the above
properties when deciding if an ambient device provides an
appropriate choice of display for exposing context
information to the user.
Based on our recent work with context information, we have
witnessed a clear trend between the need to “ask the right
question” of the information and the ease in which it can be
presented using ambient technology. The question we
bring to the workshop is : “to what extent can views of
information be adapted to render it suitable for ambient
presentation?” The complex interplay of factors involved in
choosing adequately processed data for visualisation via
ambient display will benefit from cross-collaboration
between computer scientists, visual and interaction
designers and psychologists.
ACKNOWLEDGMENTS
This work is partially supported by Science Foundation
Ireland under grant number 04/RPI/1544, “Secure and
Predictable Pervasive Computing.”
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